detect face occlusion

I am using the python SDK. FaceAnalysis returns many variables but I don't know how to determine if a face is occluded. Many images come back with a high det_score and valid looking numbers for the other parameters such bbox, pose, eye, nose and mount locations etc, but the face is clearly occluded. Is there some method to detect if the face is occluded. These 3 examples all had a det_score above .75